Rear view mirror apparatus and method for controlling the same

ABSTRACT

A rear view mirror having a first portion and a second portion. The reflectance of the first portion is variably controlled. The reflectance of the second portion is also variably controlled, though independently from the first portion.

BACKGROUND OF THE INVENTION

The present invention relates to door mirrors and rear view mirrors thatare employed in automobiles. More particularly, the present inventionpertains to mirrors having a plurality of reflectors.

Mirrors having an aspheric reflector and a spherical reflector are knownin the art. In such mirrors, the average radius of curvature of theaspheric reflector is greater than the radius of curvature of thespherical reflector. Accordingly, a mirror having an aspheric reflectorhas a wider view than a mirror having spherical or flat reflectors.

However, when a door mirror has an aspheric reflector, the continuouslyvarying radius of curvature of the reflector reflects an imbalancedimage and may thus cause the driver to misperceive distances. For thesame reason, a rear view mirror having reflectors with differing radiiof curvature to provide a wider view may also cause the driver tomisperceive distances.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide amirror that improves the visibility of images without confusing thedriver.

To achieve the above objectives, the present invention provides a rearview mirror apparatus for a vehicle, which includes a first mirrorportion, a second mirror portion located near the first mirror portion,a reflectance regulating means associated with the first mirror portionto regulate the reflectance of the first mirror portion, and a controlcircuit for controlling the reflectance of the first mirror portionbased on current driving conditions by regulating a characteristic ofthe reflectance regulating means based on current driving conditions.

Also, the present invention provides a method of controlling a rear viewmirror including generating a turning signal when a predeterminedcondition indicating that the vehicle is changing direction is met,generating a second signal when a predetermined condition indicatingthat relatively strong light is being emitted from behind the vehicle ismet, and increasing the reflectance of a first mirror part of amulti-part mirror when the signals indicate that the vehicles is turningin the absence of relatively strong rearward light.

Other aspects and advantages of the present invention will becomeapparent from the following description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention that are believed to be novel areset forth with particularity in the appended claims. The invention,together with objects and advantages thereof, may best be understood byreference to the following description of the presently preferredembodiments together with the accompanying drawings in which:

FIG. 1 front view of a door mirror according to a first embodiment ofthe present invention;

FIG. 2 is a top plan view showing a mirror body of the mirror of FIG. 1;

FIG. 3 is a schematic top plan view showing the structure of the mirrorbody in the first and second embodiments;

FIG. 4 is a block diagram showing the electric structure for variablycontrolling the reflectance of the first and second EC layers;

FIG. 5 is a rear view mirror according to a second embodiment of thepresent invention;

FIG. 6 is a top plan view showing the mirror body of the mirror of FIG.5;

FIG. 7 is a schematic top plan view showing the mirror body structure ofa mirror according to a further embodiment of the present invention;

FIG. 8 is a schematic top plan view showing the mirror body structure ofa mirror according to a further embodiment of the present invention; and

FIG. 9 is a schematic top plan view showing the mirror body structure ofa mirror according to a further embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment according to the present invention will now bedescribed with reference to FIGS. 1 to 9. FIG. 1 is a front view showinga door mirror 1 having improved visibility. The door mirror 1 has amirror body 4, which includes a first, or outer portion 3 and a second,or inner portion 2. In this embodiment, the first portion 3 is asphericconvex, and the second portion 2 is spherical convex.

The door mirror 1 is mounted on the left and right doors of anautomobile. The left and right door mirrors 1 are symmetric about avertical plane that longitudinally bisects the automobile. Therefore,the description will focus primarily on the right door mirror 1. Thefirst portion 3 of the right door mirror 1, which widens the right viewfor a driver, is located to the right of the second portion 2. The firstportion 3 of the left door mirror 1 is located to the left of the secondportion 2.

In this embodiment, the average radius of curvature of the first portion3 is greater than the radius of curvature of the second portion 2. Arear light sensor 5 is arranged on the lower portion of the mirror body4. The light sensor 5 has an exposed light receiving portion.

As shown in FIG. 3, the mirror body 4 has a first reflector 11, whichincludes-a reflective film 13 c, and a second reflector 12, whichincludes a reflective film 14 c. The first reflector 11, which isassociated with the first portion 3, includes a first piece of glass 15and a first electrochromic (EC) layer 13. The first EC layer 13, whichserves as a first variable reflectance portion, is located in front of,or on the inner surface (i.e., upper side as viewed in FIG. 3) of thefirst piece of glass 15. The second reflector 12, which is associatedwith the second portion 2, has a second piece of glass 16 and a secondEC layer 14. The second EC layer 14, which serves as a second variablereflectance portion, is located in front of, or on the inner surface of,or on the inner surface of the second piece of glass 16.

The first EC layer 13 includes a transparent electrode 13 a, a coloringfilm 13 b, and a reflective film 13 c, which serves as a counterelectrode. The transparent electrode 13 a is fixed to the first piece ofglass 15. The reflective film 13 c extends parallel to the transparentelectrode 13 a with the coloring film 13 b located in between. Coloringof the coloring film 13 b occurs when a positive electric potential isapplied to the transparent electrode 13 a or the reflective film 13 cand a negative electric potential is applied to the other. To decolorthe coloring film 13 b, the negative electric potential and the positiveelectric potential are reversed.

In this embodiment, the coloring film 13 b is colored when a positiveelectric potential is applied to the transparent electrode 13 a and anegative electric potential is applied to the reflective film 13 c. Thecoloring of the coloring film 13 b substantially blocks the transmissionof light to the reflective plate 13 c. In the colored state, thevisibility of the image reflected in the first piece of glass 15 islowered.

Furthermore, in this embodiment, the coloring film 13 b is decoloredwhen a negative electric potential is applied to the transparentelectrode 13 a and a positive electric potential is applied to thereflective film 13 c. The decoloring of the coloring film 13 b permitsthe transmission of light to the reflective plate 13 c. In the decoloredstate, the visibility of the image reflected in the first piece of glass15 is increased. Like the first EC layer 13, the second EC layer 14includes a transparent electrode 14 a, a coloring film 14 b, and areflective film 14 c, which function in the same manner as those of thefirst EC layer 13.

The electric structure for variably controlling the reflectance of thefirst and second EC layers 13, 14 will now be described with referenceto the block diagram shown in FIG. 4.

As shown in FIG. 4, a turn signal switch 21 is connected to one of thetwo input terminals of an NOR circuit 22. A turn indicator lever 30 ismoved to actuate the turn signal switch 21 and send an ON signal(H-level signal) to the NOR circuit 22. The turn signal switch 21 isactuated, for example, when the driver moves the turn signal upward ordownward to indicate that the automobile will turn.

The other input terminal of the NOR circuit 22 is connected to asteering angle sensor 24 by way of a signal processing circuit 23. Thesteering angle sensor 24 detects the steering angle of a steering wheel31. The signal processing circuit 23 sends an H-level signal to the NORcircuit 22 when the steering angle becomes equal to or greater than apredetermined threshold value.

The output terminal of the NOR circuit 22 is connected to one of the twoinput terminals of an OR circuit 25. The other input terminal of the ORcircuit 25 is connected to the output terminal of a glare detectioncircuit 26. The glare detection circuit 26 is connected to an ambientlight sensor 27 and the rear light sensor 5. The ambient light sensor 27is located near the door mirror 1 to detect the intensity of light atthat location. The rear light sensor detects the intensity of the lightradiated from the rear. The glare detection circuit 26 electricallyprocesses the difference between the light intensity detected by theambient light sensor 27 and that detected by the rear light sensor 5.The processing result is then sent to the OR circuit 25 from the glaredetection circuit 26.

The output terminal of the OR circuit 25 is connected to the inputterminal of a first drive circuit 28, which is further connected to thefirst EC layer 13. The first drive circuit 28 variably controls thereflectance of the first EC layer 13. That is, the first drive circuit28 applies a negative electric potential to the transparent electrode 13a and a positive electric potential to the reflective film 13 c whenreceiving an L-level signal from the OR circuit 25. Under suchconditions, the first EC layer 13 enters a decolored state. On the otherhand, the first drive circuit 28 applies a positive electric potentialto the transparent electrode 13 a and a negative electric potential tothe reflective film 13 c when receiving an H-level signal from the ORcircuit 25. Under such conditions, the first EC layer 13 enters acolored state.

The output terminal of the glare detection circuit 26 is also connectedto the input terminal of a second drive circuit 29. The second drivecircuit 29 variably controls the reflectance of the second EC layer 14.That is, the second drive circuit 29 applies a negative electricpotential to the transparent electrode 14 a and a positive electricpotential to the reflective film 14 c when receiving an L-level signalfrom the glare detection circuit 26. Under such conditions, the secondEC layer 14 enters a decolored state. On the other hand, the seconddrive circuit 29 applies a positive electric potential to thetransparent electrode 14 a and a negative electric potential to thereflective film 14 c when receiving an H-level signal from the glaredetection circuit 26. Under such conditions, the second EC layer 14enters a colored state.

In this embodiment, the first and second drive circuits 28, 29 serve asa controller. The turn signal switch 21, the signal processing circuit23, the steering angle sensor 24, and the NOR circuit 22 serve as afirst trigger, while the rear light sensor 5, the glare detectioncircuit 26, and the ambient light sensor 27 serve as a second trigger.

A non-turning state refers to a state in which the turning signal switch21 remains off and the steering wheel angle remains lower than thepredetermined threshold value. When the vehicle is in the non-turningstate and a relatively strong light is not being radiated from rearwardvehicles (e.g., when driving in the daytime), the door mirror 1 operatesas described below.

When the turn signal switch 21 is off, an OFF signal (L-level signal) issent to one of the input terminals of the NOR circuit 22. The otherinput terminal of the NOR circuit 22 receives a further L-level signalfrom the signal processing circuit 23 if the steering wheel angle islower than the predetermined threshold value. Accordingly, the L-levelsignals sent to the two input terminals of the NOR circuit 22 causes theNOR circuit 22 to output an H-level signal. The H-level signal is sentto one of the input terminals of the OR circuit 25.

If the rear light sensor 5 does not receive a relatively strong lightradiated by rearward vehicles (e.g., when driving in the daytime), thedifference between the light intensity detected by the ambient lightsensor 27 and that detected by the rear light sensor 5 is small. In suchstate, the glare detection sensor 26 sends an L-level signal to theother input terminal of the OR circuit 25. Since one of input terminalsof the OR circuit 25 receives an H-level signal, the OR circuit 25outputs an H-level signal, which is sent to the first drive circuit 28.

When receiving the H-level signal, the first drive circuit 28 applies apositive electric potential to the transparent electrode 13 a and anegative electric potential to the reflective film 13 c so that thefirst EC layer 13 is colored. In this state, the coloring film 13 b iscolored to substantially block the transmission of light to thereflective plate 13 c and thereby decrease the reflectance of the firstEC layer 13, which is associated with the first portion 3. This lowersthe visibility of the image reflected by the first piece of glass 15.

A turning state is a state in which either the turning signal switch 21is turned on or the steering wheel angle is equal to or greater than thepredetermined threshold value. If the vehicle is in the turning state,and a relatively strong light is not radiated from rearward vehicles(e.g., when driving in the daytime), the door mirror 1 operates asdescribed below.

Since the turn indicator lever 30 is moved or the steering wheel angleis equal to or greater than the predetermined threshold value, at leastone of the two input terminals of the NOR circuit 22 receives an H-levelsignal. In this case, an L-level signal is output from the NOR circuit22 and sent to one of the input terminals of the OR circuit 25. Theother input terminal of the OR circuit 25 also receives an L-levelsignal because, as stated above, in this example, no glare is present.Since L-level signals are received by both input terminals of the ORcircuit 25, the OR circuit 25 sends an L-level signal to the first drivecircuit 28.

When receiving an L-level signal, the first drive circuit 28 applies anegative electric potential to the transparent electrode 13 a and apositive electric potential to the reflective film 13 c to decolor thefirst EC layer 13. When decolored, the coloring film 13 b of the firstEC layer 13 becomes transparent and permits the reflection of externallight with the reflective plate 13 c. Accordingly, the reflectance ofthe first EC layer 13, which is associated with the first portion 3,increases. Thus, the visibility of the image reflected in the firstpiece of glass 15 increases and provides a wider view, which is helpfulto the driver when turning.

In this embodiment, the reflectance of the first EC layer 13, which isassociated with the first portion 3, increases when turning in theabsence of glare. This increases the visibility of the image reflectedin the first piece of glass 15 and provides a wider view in which thedriver can recognize images. On the other hand, the reflectance of thefirst EC layer 13 decreases when turning in the presence of glare orwhen not turning. This decreases the visibility of the image reflectedby the first piece of glass 15, which prevents the driver frommisperceiving distances due to the varying radius of curvature.

The operation of the door mirror 1 when a relatively strong light isradiated from a rearward vehicle (e.g., when driving at nighttime or intunnels) in the non-turning state will now be described.

If a strong light from a rearward vehicle is received by the rear lightsensor 5 in the non-turning state, the difference between the lightintensity detected by the ambient light sensor 27 and that detected bythe rear light sensor 5 becomes large. Thus, one of the input terminalsof the OR circuit 25 receives an H-level signal from the glare detectioncircuit 26. The other input terminal of the OR circuit 25 also receivesan H-level signal because the NOR circuit 22 outputs an H-level signalin the non-turning state. Since the two input terminals of the ORcircuit 25 both receive H-level signals, the OR circuit 25 outputs anH-level signal.

The H-level signal output by the OR circuit 25 is sent to the firstdrive circuit 28. The first drive circuit 28 then applies a positiveelectric potential to the transparent electrode 13 a and a negativeelectric potential to the reflective film 13 c to color the first EClayer 13. Accordingly, the coloring of the coloring film 13 b decreasesthe reflectance of the first EC layer 13, which corresponds to the firstportion 3.

Furthermore, when the second drive circuit 29 receives the H-levelsignal from the glare detection circuit 26, the second drive circuit 29applies a positive electric potential to the transparent electrode 14 aand a negative electric potential to the reflective film 14 c to colorthe second EC layer 14. Accordingly, the coloring of the coloring film14 b decreases the reflectance of the second EC layer 14, which isassociated with the second portion 2. As a result, glare does notinterfere with the driver's recognition of images reflected in the firstand second pieces of glass 15, 16.

The operation of the door mirror 1 when a relatively strong light isradiated from a rearward vehicle (e.g., when driving in the nighttime orin tunnels) in the turning state will now be described.

If a relatively strong light from a rearward vehicle is received by therear light sensor 5 in the turning state, one of the input terminals ofthe OR circuit 25 receives an L-level signal from the NOR circuit 22,while the other input terminal of the OR circuit 25 receives an H-levelsignal from the glare detection circuit 26. Thus, the OR circuit 25outputs an H-level signal. Accordingly, both first and second drivecircuits 28, 29 receive H-level signals, which colors the associatedfirst and second EC layers 13, 14. As a result, glare does not interferewith the driver's recognition of images reflected in the first andsecond pieces of glass 15, 16.

The advantages of this embodiment are described below.

(1) In the tuning state, when no glare is present, the first drivecircuit 28 decolors the first EC layer 13 to increase the reflectance ofthe first EC layer 13. This increases the visibility of the imagereflected in the first piece of glass 15 and widens the driver's view.In the non-turning state, the first drive circuit 28 colors the first EClayer 13 to decrease the reflectance of the first EC layer 13. Thisdecreases the visibility of the image reflected in the first piece ofglass 15 and prevents the driver from misperceiving distances due to thedifference in radius of curvature between the first and second pieces ofglass 15, 16. In other words, this compensates for the difference inradius of curvature between the first and second pieces of glass 15, 16.

(2) Regardless of whether the vehicle is turning, if the rear lightsensor 5 receives relatively strong light from a rearward vehicle (e.g.,when driving in the nighttime or in tunnels), the first and second drivecircuits 28, 29 color and decrease the reflectance of the associatedfirst and second EC layers 13, 14. This prevents glare from interferingwith the driver's recognition of images reflected in the first andsecond pieces of glass 15, 16.

(3) In this embodiment, electrochromic portions are employed to vary thereflectance of the door mirror 1. This results in advantages (1) and(2).

(4) The average radius of curvature of the first portion 3 is greaterthan the radius of curvature of the second portion 2. This provides awider view in comparison to a door mirror having a constant radius ofcurvature. Accordingly, if the first drive circuit 28 decolors the firstEC layer 13, the visibility of the image reflected in the first piece ofglass 15 increases, which widens the driver's view.

The operation of the door mirror 1 is also described in the followingtable.

TABLE NO TURN TURNING GLARE NO GLARE GLARE NO GLARE 1st portion coloredcolored colored decolored 2nd portion colored decolored coloreddecolored

A second embodiment according to the present invention will now bedescribed with reference to the drawings. To avoid redundancy, like orsame reference numerals are given to those components that are the sameas the corresponding components of the first embodiment.

FIG. 5 shows a rear view mirror 41 used in an automobile. The rear viewmirror 41 has a mirror body 4, which includes a flat portion 42 andcurved portions 43. The curved portions 43 are located on each side ofthe flat portion 42 to widen the left and right views. Since the radiusof curvature of the flat portion 42 is zero, the radius of curvature ofthe curved portions 43 is greater than that of the flat portion 42.

The mirror body 4 has a first EC layer 13 located in front of, or on theinner surface of a first piece of glass 15, which corresponds to thecurved portion 43, and a second EC layer 14 located in front of, or onthe inner surface of a second piece of glass 16, as shown in FIG. 3. Thereflectances of the first and second EC layers 13, 14 are variablycontrolled by the same electric structure as the first embodiment (FIG.4).

In addition to advantages (1) to (4) of the first embodiment, the secondembodiment has the advantage described below.

(5) The curved portions 43, which are located on the left and rightsides of the flat portion 43, each have a radius of curvature that isgreater than the flat portion 43. Therefore, the rear view mirror 41 hasa wider view in comparison with a totally flat rear view mirror.Accordingly, if the first drive circuit 28 decolors the first EC layer15, the reflectance of the first EC layer 13 increases. This increasesthe visibility of the image reflected by the first piece of glass 15 andprovides a wider view. Furthermore, since the curved portions 43 arelocated on the left and right sides of the flat portion 42, bothleftward and rightward views are widened simultaneously to assist thedriver in recognizing images at the left and right sides of the vehicle.

It should be apparent to those skilled in the art that the presentinvention may be embodied in many other specific forms without departingfrom the spirit or scope of the invention. Particularly, it should beunderstood that the present invention may be embodied in the followingforms.

In the illustrated embodiments, signals (H-level and L-level) are outputby the turn signal switch 21 and the signal processing circuit 23, whichform the first trigger, to automatically vary the reflectances of thefirst portion 3 of the door mirror 1 or the curved portions 43 of therear view mirror 41. However, the reflectances of the first portion 3and the curved portions 43 may be varied by employing a manual switch,which would serve as a first trigger, in lieu of the turn signal switch21 and the signal processing circuit 23.

In the illustrated embodiments, the first drive circuit 28 variablycontrols the reflectance of the first EC layer 13, while the seconddrive circuit 29 variably controls the reflectance of the second EClayer 14. However, the reflectances of the first and second EC layers13, 14 may be variably controlled by a single drive circuit.

In the illustrated embodiments, electrochromic portions are employed asthe first and second variable reflectance portions. However, a liquidcrystal layer may be employed instead of the EC layer as the first andsecond variable reflectance portions.

In the illustrated embodiments, the second EC layer 14 is arranged incorrespondence with the second portion 2 of the door mirror 1 and theflat portion 42 of the rear view mirror 41. However, the second EC layer14 may be eliminated. That is, the door mirror 1 or the rear view mirror41 may be provided with only one EC layer in association with the firstportion 3 or the curved portion 43.

In the rear view mirror 41 of the second embodiment, the curved portions43 are located on each side of the flat portion 42. However, the presentinvention may also be applied to a rear view mirror having a singlecurved portion 43, which is located on one side of the flat portion 42.

In the illustrated embodiments, the turn signal switch 21, the signalprocessing circuit 23, and the steering angle sensor 24 form the firsttrigger, which variably controls the reflectance of the first EC layer13 with the signals output from the turn signal switch 21 and the signalprocessing circuit 23. However, the turn signal switch 21 may beeliminated from the first trigger. In this case, the reflectance of thefirst EC layer 13 is variably controlled only by the signals output bythe signal processing circuit 23. Alternatively, the signal processingcircuit 23 may be eliminated from the first trigger. In this case, thereflectance of the first EC layer 13 is variably controlled only by thesignals output by the turn signal switch 21.

In the illustrated embodiments, curved portions are employed to form themirror body 4. However, the present invention may also be applied to amirror body formed from more than one flat portion.

In the first and second embodiments, the mirror body 4 includes thefirst piece of glass 15, the first EC layer 13 located at the inner sideof the first piece of glass 15, the second piece of glass 16, and thesecond EC layer 14 located in front of the second piece of glass 16, asshown in FIG. 3. However, the structure of the mirror body 4 may bealtered as shown in FIGS. 7 to 9.

As shown in 7, the mirror body 4 may be formed by arranging the first EClayer 13 on the rear side, or outer surface (lower side as viewed in 7)of the first piece of glass 15 and by arranging the second EC layer 14on the rear side of the second piece of glass 16. Alternatively, asshown in FIG. 8, the mirror body 4 may be formed by arranging the firstEC layer 13 between a pair of first pieces of glass 15 and the second EClayer 14 between a pair of second pieces of glass 16. As another option,as shown in 9, the mirror body 4 may be formed by arranging the coloringfilm 13 b between a pair of transparent electrodes 13 a and the coloringfilm 14 b between a pair of transparent electrodes 14 a. The coloringfilm 13 b and the transparent electrodes 13 a are arranged between apair of first pieces of glass 15, while the coloring film 14 b and thetransparent electrodes 14 a are arranged between a pair of second piecesof glass 16. The reflective film 13 c is arranged at the inner side ofthe rear first piece of glass 15 (the upper one as viewed in FIG. 9),while the reflective film 14 c is arranged at the inner side of the rearsecond piece of glass 16 (the upper one as viewed in FIG. 9).

The present examples and embodiments are to be considered asillustrative and not restrictive, and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalence of the appended claims.

What is claimed is:
 1. A rear view mirror apparatus for a vehiclecomprising: a first mirror portion; a second mirror portion located nearthe first mirror portion; a reflectance regulating means associated withthe first mirror portion to regulate the reflectance of the first mirrorportion; a trigger that generates a tuning signal when the vehicle meetsa predetermined condition indicating a change of vehicle direction; anda control circuit for controlling the reflectance of the first mirrorportion based on the state of the turning signal by regulating acharacteristic of the reflectance regulating means.
 2. The rear viewmirror apparatus according to claim 1, wherein the reflectanceregulating means is a first reflectance regulating means, and a secondreflectance regulating means covers the second mirror portion, whereinthe control circuit controls the reflectance of both mirror portionsbased on current driving conditions.
 3. The rear view mirror apparatusaccording to claim 1, wherein the trigger is a first trigger, and theapparatus further comprises: a second trigger that generates a glaresignal when a predetermined condition indicating relatively strong lightemitted from behind the vehicle is met, wherein the control circuitcontrols the reflectance of the first mirror portion based on the statesof the turning signal and the glare signal.
 4. The rear view mirrorapparatus of claim 1, wherein the vehicle includes a turn-signal leverconnected to the control circuit, and operation of the turn-signal leverin the vehicle produces the turning signal.
 5. The rear view mirrorapparatus of claim 1, wherein the vehicle includes a steering anglesensor connected to the control circuit, and wherein the triggerproduces the turning signal when the steering angle sensor detects thatthe steering angle exceeds a predetermined value.
 6. The rear viewmirror apparatus of claim 3, wherein the second trigger includes anambient light sensor, a rear light sensor, and a glare detection circuitthat generates the glare signal based on the difference between thelevel of ambient light and the level of light coming from behind thevehicle.
 7. The rear view mirror apparatus according to claim 1, whereinthe reflectance regulating means is an electrochromic layer.
 8. The rearview mirror apparatus according to claim 1, wherein the reflectanceregulating means is a liquid crystal layer.
 9. The rear view mirrorapparatus according to claim 1, wherein the first mirror portion isconvex.
 10. The rear view mirror apparatus according to claim 9, whereinthe first mirror portion is spheric and the second mirror portion isaspheric.
 11. A rear view mirror apparatus for a vehicle comprising: afirst mirror portion; a second mirror portion located near the firstmirror portion; a layer having variable light characteristics andcovering one surface of the first mirror portion to regulate thereflectance of the first mirror portion; a first trigger that generatesa turning signal when the vehicle meets a predetermined conditionindicating a change of vehicle direction; a second trigger thatgenerates a glare signal when a predetermined condition indicatingrelatively strong light emitted from behind the vehicle is met; and acontrol circuit for controlling the reflectance of the first mirrorportion based on the states of the turning signal and the glare signalby regulating the light characteristics of the layer.
 12. The rear viewmirror apparatus according to claim 11, wherein the layer is a firstvariable light transmission layer, and a second variable lighttransmission layer covers the second mirror portion, wherein the controlcircuit controls the reflectance of both mirror portions based oncurrent driving conditions by regulating the light transmission of thevariable light transmission layers.
 13. The rear view mirror apparatusof claim 11, wherein the vehicle includes a turn-signal lever connectedto the control circuit, and operation of the turn-signal lever in thevehicle produces the turning signal.
 14. The rear view mirror apparatusof claim 11, wherein the vehicle includes a steering angle sensorconnected to the control circuit, and wherein the first trigger producesthe turning signal when the steering angle sensor detects that thesteering angle exceeds a predetermined value.
 15. The rear view mirrorapparatus of claim 11, wherein the second trigger includes an ambientlight sensor, a rear light sensor, and a glare detection circuit thatgenerates the glare signal based on the difference between the level ofambient light and the level of light coming from behind the vehicle. 16.A method of controlling a rear view mirror for a vehicle comprising:generating a turning signal when a predetermined condition indicatingthat the vehicle is changing direction is met; generating a glare signalwhen a predetermined condition indicating that relatively strong lightis being emitted from behind the vehicle is met; increasing thereflectance of a first mirror part of a multi-part mirror when thesignals indicate that the vehicles is turning in the absence ofrelatively strong rearward light.
 17. The method of controlling a rearview mirror of claim 16 including reducing the reflectance of the firstmirror part when relatively strong light is being emitted from behindthe vehicle.
 18. The method of controlling a rear view mirror of claim16 including increasing the reflectance of a second mirror part of themulti-part mirror in the absence of relatively strong rearward light anddecreasing the reflectance of the second mirror part in the presence ofrelatively strong rearward light.
 19. A rear view mirror apparatus for avehicle comprising: a first mirror portion; a second mirror portionlocated near the first mirror portion, wherein the average radius ofcurvature of the first mirror portion is greater than that of the secondmirror portion; a reflectance regulator associated with the first mirrorportion to regulate the reflectance of the first mirror portion; and acontrol circuit for controlling the reflectance of the first mirrorportion by regulating a characteristic of the reflectance regulator,wherein the control circuit increases the reflectance of the firstmirror portion to widen the driver's view when the vehicle meets apredetermined condition, wherein the predetermined condition indicates achange of vehicle direction, and the control circuit decreases thereflectance of the first mirror portion to prevent the driver frommisperceiving distances when the vehicle does not meet the predeterminedcondition.
 20. The rear view mirror apparatus according to claim 19,wherein the reflectance regulator is a first regulator, and a secondreflectance regulator covers the second mirror portion, wherein thecontrol circuit controls the reflectance of both mirror portions basedon current driving conditions of the vehicle.
 21. The rear view mirrorapparatus according to claim 19, wherein the vehicle includes aturn-signal lever connected to the control circuit, wherein the controlcircuit increases the reflectance of the first mirror portion when theturn-signal lever is operated.
 22. The rear view mirror apparatusaccording to claim 19, wherein the vehicle includes a steering anglesensor connected to the control circuit, wherein the control circuitincreases the reflectance of the first mirror portion when the steeringangle sensor detects that the steering angle exceeds a predeterminedvalue.
 23. The rear view mirror apparatus according to claim 20, furthercomprising an ambient light sensor and a rear light sensor, wherein thecontrol circuit controls the reflectance of both mirror portions basedon the difference between the level of ambient light and the level oflight coming from behind the vehicle.